Casio Basic is the built-in programming language on all of Casio's graphing calculators. It is a scripting language, which means that it is interpreted and executed one token or instruction at a time as it runs. Conversely, a compiled language is fully converted into machine language before it runs, so it generally runs much faster. Casio Basic is called such for the similarity between the dialect of the language and various versions of BASIC.

Casio Basic is extremely simple to learn and use, as most of the commands are written in plain English or easily comprehended abbreviations, and are generally self-explanatory. For example, it is not very hard to recognize that the ClrText command clears all of the text on the screen. You can create Casio Basic programs on the computer and then transfer them to your calculator using a USB cable, or on the calculator itself through the program editor. When an error is encountered in Casio Basic, the calculator gives the user the option to go to the problem, which makes debugging much easier.

Because Casio Basic code is read and acted on as it is executed, it loses much of its speed; doing anything involving calculations or graphics can be painfully slow. Really, the speed of Casio Basic comes nowhere close to the speed of assembly. You just need to play an assembly game (such as Super Mario or Phoenix) to see the great difference in speed. Casio Basic also does not have low-level access to the calculator's hardware. While this is intentionally done to prevent potential misuse, it has the result of limiting the quality of Casio Basic programs.